One-step synthesis of highly efficient CaO-based CO2 sorbent pellets via gel-casting technique

- Efficient CaO pellets were synthesized with one step via gel-casting technique.
- Microcrystalline cellulose is effective to improve the sorbent structure.
- Synthesized CaO pellets possess good chemicophysical performance for CO2 capture.
- Further efforts are needed to simplify the manufacturing process of this technique.

The traditional development of CaO-based sorbents to be used in calcium looping process (CLP) consists of two steps: producing powders with improved cyclic performance by sorbent modification, followed by the subsequent granulation. However, this traditional routine is complicated and energy-consuming. Moreover, the improved performance would be weakened again during the granulation process. Hence, the implement of the modification and granulation within one step to produce CaO-based sorbents is of significant importance for CLP. This work, for the first time, proposes a simple and facile gel-casting technique to achieve the one-step synthesis of highly-efficient CaO-based sorbents pellets. The pellets modified with microcrystalline cellulose (CaO-MC) achieved considerable CO2 capture capacity of ~ 0.48 g CO2/g sorbent at the 25th cycle under the mild calcination condition and retained relatively excellent performance of 0.41 g/g over 25 moderate cyclic tests, higher than those of the unmodified pellets (CaO-pellet). The decomposition of microcrystalline cellulose in CaO-MC does not change the cubic crystal structure of CaO, but brings more pores that contribute a lot to its superior CO2 capture performance. Moreover, all synthesized pellets possess good attrition resistance, indicating the applicability of the prepared pellets to the application in CLP.

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